Week 3 - 2D meshing for sheet metal

Hood Meshing

Aim: To perform geometry cleanup, mid surface extraction, and 2D shell meshing for the hood component of a car to satisfy the following quality criteria,

S.No	Quality Criteria	Value
1	Target/Average length	5
2	Minimum Length	2
3	Maximum Length	7
4	Aspect	3
5	Warpage	15
6	Skewness	45
7	Jacobian	0.7
8	Minimum Quad Angle	45
9	Maximum Quad Angle	135
10	Minimum Tria Angle	30
11	Maximum Tria Angle	120
10	Tria Percentage	15

Procedure:

Import the hood model in ANSA. The hood model contains five individual components i.e,

• Outer panel
• Inner panel
• Latch reinforcement
• L&R hing reinforcement

After importing the model , properly analyze and understand the geometry. There might be several geometrical errors like missing/distorted surfaces, intersecting surfaces, etc. It is important to clear all these errors before starting meshing.To ensure that all the surfaces are connected properly Faces>Topo . Geometry check is performed by going to Checks>Geometry.

The errors are fixed using fix command in geometry check.

Mid Surface Extaction:

Mid surface is extracted using Mid surface feature in Faces > Midsurface and each mid surface is kept into different Pid using set Pid option.

• Outer panel

• Inner panel

• Latch reinforcement

• L&R hing reinforcement

Mesh Parameters & Quality criteria:

Meshing:

Meshing is done using the Mesh generation>Best tool. Then, the created mesh is refined using the Shell Mesh>Reconstruct tool. It is ensured that there are no rotating quads. Also, trias are kept as low as possible. While dealing with trias, the following things need to be ensured.

• No back to back trias touching each other
• No opposite trias
• No trias touching the edges
• No trias on a feature
• Low concentration of trias in a region

To deal with trias, the following tools are used,

• Elements>Split, to split an element and move tria forward
• Elements>Swap, to move the tria left or right

After modifying the mesh, Shell Mesh>Smooth tool is used to smoothen the flow of the mesh. Any elements failing for quality criteria

Following is the obtained mesh;

• Outer panel

• Inner panel

• Latch reinforcement

• L&R hing reinforcement

Conclusion:

Geometry cleanup, mid surface extraction, and 2D meshing of the given hood model were successfully done. And all the elements pass the quality criteria. All the features in the model are captured properly with good mesh flow with low tria .